Body mass index, or BMI, is a number scale that estimates the amount of body fat based on an individual's weight and height. The index provides a general guideline for assessing overall health risk. People who are overweight or obese have a higher risk of heart disease, diabetes, high blood pressure and high cholesterol.
The Index Categories
The categories for BMI predict body fat percentages based on a calculation of height and weight. According to the BMI scale, a calculation below 18.5 is underweight, measurements between 18.5 to 24.9 are normal, 25 to 29.9 are overweight, and 30 to 39.9 obese and over 40 morbidly obese. To estimate your BMI, MedlinePlus recommends multiplying 703 by your weight in pounds; divide the result by height in inches, and again divide that result by your height in inches. Someone who weighs 150 lbs. and is 5 feet 4 inches tall would have a 25.7 BMI.
Accuracy
The body mass index rating is only a guideline. For athletic or muscular individuals, the index will not accurately reflect their percentage of body fat since muscle is more dense than fat. The index may also be inaccurate for screening seniors and children since the body mass index can not accurately measure bone mass. To estimate BMI in children, health screenings involve a special method that uses percentile ranking based on age, sex, height and weight. Seniors can request a bone density test to assess their bone mass, which will also give a highly accurate body fat percentage as well. The best use of BMI is for screening purposes, many techniques are available for accurately measuring body fat and lean body mass to determine a healthy weight.
Risk Assessment
The BMI is used to assess individual risk for serious health complications. If your BMI measures put you at high risk, a waist circumference measurement may also be taken. Excess fat carried around the waist puts stress on internal organs and puts individuals at a higher risk of heart disease and diabetes. If your BMI measures as high risk, a referral to a health-care professional may follow for a full health assessment.
Reducing BMI
Reducing your body mass index results in burning more calories, or energy, than you consume. One way this can be accomplished is by reducing total caloric intake. A reduction of just 500 calories per day can result in a loss of 1 lb. per week. For some people, just eliminating two regular sodas or blended coffee drinks per day can result in significant weight loss over time. Another way to reduce your body mass index is to increase your exercise and physical activity. Exercise is structured, planned activity involving the major muscle groups. Physical activity includes daily activities such as housework, moving rather than sitting, parking farther away in parking lots or taking the stairs. Doing more of this each day can double your energy output for the day. Strength training helps reduce body fat. Because muscle tissue is very active, it burns more fat. It also strengthens bones.
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